Add alias and prelude shorthand tags

[gilch]

Now you can say

hissp..prelude#:

instead of the longer

(hissp.._macro_.prelude)
;; or
(hissp.macros.._macro_.prelude)

although any of them work. While a : argument uses the current module's global namespace, you can specify a different one (e.g., to get Ensue without all the star imports, see the wiki). This should be considered the current standard way to do it (at least for Hissp 0.5), but we're still not to 1.0, and things that have changed recently are less likely to be stable. I'm still considering the alternatives in #257 for after version 0.5.

The main alternative to the prelude is alias, which now also has a shorthand tag.

hissp..alias## spam foo.bar.

If you don't specify the qualifier, it assumes you want the bundled macros. This usage is now demonstrated in test_macros.lissp with the following line:

hissp..alias#*

[gilch]

Ah, so that's why I was using suppress instead of a try/except before. Those lines aren't really reachable by the tests. I might change that back later. I was at "100%" code coverage at one point, but I can't generate coverage data for the .lissp modules, so that was probably illusory even at the time. I do have extensive doctests for the macros, but there are probably some edge cases I missed. "Covered" doesn't actually mean tested, although "not covered" means it isn't (automatically). I'd eventually like to try mutation testing #46, but I'm not sure how to make that work on the .lissp either. I might have to implement it myself.

[gilch]

Tests are green now, even if I lost a little coverage percentage. Merging.